Continuous mining machine with roof contacting means



March 18, 1958 w -row}; 2,827,274

CONTINUOUS MINING MACHINE WITH ROOF CONTACTING MEANS Filed Feb. 11, 1955 3 Sheets-Sheet l Tiql- INVENTOR.

WiLLIAM N. POUNDSTONE ATTORNEY March 18, 1958 w. N. POUNDSTONE 2,827,274

CONTINUOUS MINING MACHINE WITH ROOF CONTACTING MEANS 3 Sheets-Sheet 2 Filed Feb. 11, 1955 NEE DLE VALVE 5% HYDRAULIC FLU-ID RESERVOR INVENTOR. WILLIAM N. POUNDSTONE ATTORNEY March 18, 1958 w. N. POUNDSTONE 2,327,274

CONTINUOUS MINING MACHINE WITH ROOF CONTACTING MEANS Filed Feb. 11, 1955 3 Sheets-Sheet s INVENTOR. WILLIAM N. POUNDSTONE Y ATTORNEY United States Patent CONTINUOUS MINING MACHlNE WETH ROOF CONTACTING MEANS William N. Poundstone, Morgantown, W. Va, assignor to Pittsburgh Consolidation Coal Company, Pittsburgh, Pa., a corporation of Pennsylvania Application February 11, 1955, Serial No. 437,529

Claims. (Cl. 262-7) The present invention relates to an improved continuous mining machine. More particularly, it relates to coal mining machines which are adapted to cut, gather and remove minable material.

A great variety of continuous coal mining machines have been proposed; many types are commercially available. Despite their apparent advantages, i. e., both the cutting and removing operations are performed by one machine, these continuous mining machines have been slow in gaining acceptance in the industry.

Existing machines are quite expensive, quite heavy and cumbersome. Their expense can be justified only if high coal production rates can be realized.

A typical continuous mining machine comprises a frame, mounted upon endless treads, and a heavy cutting head at the forward end of the frame for cutting into a seam of coal in advance of the machine. A conveyer is provided from the forward end of the machine extending backward to discharge dislodged coal into shuttle cars or belt conveyer trains. Continuous loading devices are provided at the forward end of the machine to move the dislodged coal toward the machine conveyer.

One major deficiency of existing continuous mining machines is the limited traction which can be developed. Existing machines depend upon their weight alone to develop traction. To increase available traction, weight has been added as ballast to existing machines in the form of added structural members and metal weights. While this additional ballast increases the traction, the added weight of the modified machine produces problems in maneuvering the machine through underground mine passageways. Moreover the added weight increases the cost of the machine. The current trends in continuous mining contemplate the use of the mining machine itself to pull flexible and extensible conveyer systems attached directly to the mining machine. These trends require added traction for pulling which will of course reduce the traction available for the actual coal cutting operation. With existing machines operating at the maximum limit of the traction which can be developed, there is no additional traction available for this increased towing demand without sacrificing the cutting rate of the machine. Moreover, regardless of the towing demand, there is no additional traction available for increasing the cutting rates of the machine.

Even with added ballast in existing mining machines, the motors operating the cutter head seldom attain their 7 maximum torque since the machine only rarely can develop-sutficient thrust to call upon the maximum output from the cutter head motors. If additional traction were available in-the mining machine, the thrust of the machine tending to drive the cutting device against the coal seam would be increased, and increased capacity motors could be installed for operating the cutting heads, thereby increasing the output of the machine.

Some existing machines have been modified by the installation of larger grousers on the endless treads which are used to move the frame of the machine. While these deeper grousers do increase the traction in certain conditions, the amount of increased traction from this source is limited and they have the disadvantage of creating a bad bottom condition resulting from their digging action on the floor-of the mine.

The power which can be applied to the cutting head in existing-continuous mining machines is limited by the forward thrust which can be developed through the endless treads. If an attempt is made to increase the advance thrust by increasing the speed of the endless treads, the treads will increase in speed until they begin to slip on the bottom, digging holes and ruts in the mine floor. At the moment slippage occurs, the thrust of the machine decreases sharply.

Stability and rigidity of the cutting head in existing mining machines is maintained solely through the weight of the machine itself. As the cutter bits encounter a hard pocket in the mining face, the entire machine rises up in reaction; only the weight of the machine resists the sudden application of increased resistance to the movement of the cutter bits. One reason that cutter bit breakage has been excessive in existing continuous mining machines is this lack of rigidity in the cutting head. The individual bits are free to bounce from a hard area of a seam instead of being held firmly against it. Reduced cutter bit wear and breakage would be experienced if the cutter bits could be held firmly in contact with the coal face at all times, thereby approximating machine shop lathe operation.

In the present invention I have provided means for obtaining increased traction in existing mining machines without adding weight as ballast to the machine and without increasing the size of the grousers on the endless treads. My improved mining machine develops sufficient traction and accompanying increased advance thrust to permit installation of larger cutting head motors and realize their greater cutting capacity. The increased stability of the machine with respect to the mining face reduces wear and breakage of cutter bits.

To accomplish my desirable results, I have installed roof-contacting members to existing types of continuous mining machines. These roof-contacting members exert a force against the roof of the mine passageway, thereby increasing the normal force of the machine downwardly upon the endless treads. The increased normal force increases the traction which can be developed by the machine and yet permits construction of the machine without excessive weight so that its maneuverability throughout the mine, when not actually in coal cutting production, is strikingly improved. Moreover the roofcontacting members firmly position the machine within the passageway and provide the stability required to minimize cutter bit breakage by holding the cutter bits rigidly in position regardless of the nature of the coal seam.

In addition my invention permits location of the center of gravity of the mining machine more nearly toward the center of the machine frame to offset the inherent forward displacement of the center of gravity of continuous mining machines resulting from the substantial weight of the forward cutter head.

For a clearer understanding of the present invention, its objects and advantages, reference should be 'had to the following description and acompanying drawings in which:

Figure 1 is a schematic side elevation view of a mining machine adapted to practice the present invention;

Figure -2 is a schematic plan view of the mining machine shown in Figure 1;

Figure 3 is an enlarged cross sectional illustration of I ditions. comprises a 'frame 11 mounted upon endless treads 12 j V the hydraulic piston and cylinder employed in the premachine illustrating still another embodiment of the roofengaging elements of the. present invention."

The preferred embodiment of'the present invention will be described in connection with Figures 1, 2, 3, 4 and 5.' Figure 1 represents generally atypical continuous mining machine inside elevation under operating con- The machine, designated by the numeral 10,

which are driven by motor power (not shown),iusually hydraulic. The endless treads 12 engage the floor 13 of a mine passageway directly before a coal face 14. A cutting head motor and frame 15 is mounted on the forward portion of the machine frame 11 to support and drive a cutter bar 16 having a rotary cutting motion. The'cutter bar 16 is provided with cutter bit holders 17 which receive cutter bits 18. When the cutter bar 16 V rotates? about a central horizontal shaft 19, the cutter bits 13 engage the coal face 14. With the endless treads 12 advancing the machine 10 against the coal seam 14,

. in Figure; 1, it is apparent that any form of cutter head can be employed, for example, a series of individual cutter bars, oscillating cutter blades, moving endless cutter chains, and the like.

According to. my invention, I provide roof-engaging members 21 to exert an upward force against the roof of the mine passageway continuously. In the preferred embodiment the roof-engaging member 21 is a rubbertired wheel or, series of coaxial wheels, freely rotatable about 'an axle 36. To support these roof-engaging elements 21, a supporting'structure 22 is mounted on the 7 frame -11 of' the machine 10. A rail 23' is mounted in a generally horizontal'position above the frame 11 of the mining machine '10 on the supporting structure 22. Two sliding'blocks' 24 and 25.are provided which are free to slide longitudinally along the rail 23. A spring 27, supported between the supporting structure 22 and the forward sliding'block 24, is compressible with the advance of the block'24 along the rail 23 to resist further advance. V r

A pin joint journal is provided in each of the sliding upwardly extending arms 29 and 30 respectively to the blocks 24 and 25 in coplanar pivotal relation through the pin joint journals. As shown in Figure 5, the upper ends of the-arms 29 and 30 are secured in coplanar pivotal relation by means of pin 31 inserted through axially aligned pin receiving openings oin the arms'29 and 30. Fixedly mounted above the pin 31 on the upwardly extending arm 29 is a generally horizontal, circular plate 32 (see Figure having a circular pin receiving opening vertically disposed at its center. A second generally horizontal, circular plate 33 rotatably rests upon the plate 32 and has a central downwardly vertically extending pin 34 which is received by the opening in the plate 32 {to permit free rotation of the plate 33 about the pin 34.

7 separation.

4 of the mine passageway. Preferably the axis of the axle 36 is disposed ofl-center with respect to the axis of pin 34 to produce a caster action in the roof-engaging wheels 21. V

A compressive force of the wheels 21 against the roof of the mine passageway is obtained through the scissors action of the arms 29 and 30 as the sliding blocks 24 and are brought together. The latter is accomplished, as shown in Figures 1, 2 and 3, by a hydraulic ram 41 which has chamber 42 for receiving hydraulic fluid under pressure and is mounted securely withrespect to the frame 11 on the supporting structure 22. A piston 43 slides within the chamber 42 to produce longitudinal motion of a piston shaft 44 parallel to the rail 23. The piston shaft 44 at one endengages and effects movement of the sliding block 25. When the chamber 42 is filled with hydraulic fluid under pressure from conduit 52, the sliding block 25. is broughtinto proximity with the sliding block 24 to extend the wheel 21 to its maximum reach.

On the other hand, when the hydraulic fluid isiwithdrawn from the chamber 42, the piston shaft .44 retracts and the sliding blocks 24 and 25 exhibit their maximum In this position the wheel 21 is retracted out of contact with the roof of the mine and the mining machine 10 can be moved readily about the mine.

The preferred embodiment for hydraulic fluid introduction into the chamber 42 will be described by reference to Figure 4.

A hydraulic system suitably mounted on the mining machine lfl is provided which comprises a hydraulic fluid reservoir 46 for supplying hydraulic fluid through a hydraulic conduit 47 to a hydraulic pump 48. The'latter discharges high pressure hydraulic fluid continuously through a conduit 49, through a relief valve 50.10 a manually controlled two-position, three-way valve 51.

' With the valve 51 in the position shown in Figure 4, hy-

draulic fluid from the pump 48 passes through the con-.

i duit 52 through a manually controlled needle adjusting valve 53 into the hydraulic chamber 42. The normal up to about 2,000 p. s. i. or more.

l the desired maximum working pressure of the system.

The hydraulic fluid, by-passed through the valve 50,

- returns to the reservoir 46 through the conduit 54. As

i hydraulic fluid enters the chamber 42 (with the valve 51 in the position shown in Figure 4) the piston 43 advances causing the sliding'block 25 to move along the rail 23 toward the sliding block 24. Wheel 21 moves upwardly until it engages the roof-of the mine passageway. Thereupon the pressure of the hydraulic fluid in the system in- 55. p a 45 with the rail 23, a positive mechanical advantage. is

blocks 24 and 25. Pins 26 and 28 are provided tofasten '53 can be closed to traphydraulic fluid in the cylinder ,42 and valve'51 can be turned to allow hydraulic fluid creases to the desired operating value causing aforce to be exerted through the wheel 21 against the roof of the mine. lWhen the arm 30 forms an angle greater than to by -pass into the reservoir-46 through a conduit55, allowing the pump.48 to operate under low pressures. With the wheel 21 exerting an upward force against the roof jof the mine, 'an equal'reaction force acts down- Two axle bearings 37 and 38' are securely mounted on the top of plate 33 to support an axle 36 in a generally horizontal position. One or more freely rotatable wheels wardly through the arms 29 and 30m increase the normalforce of'thejfr'a'mell against the endless treads 12. .Thereupjonthe mining machine 10 commences cutting and removaloperations in which the cutter arm 16 rotates; as the'endless treads 12 advance the machine into the i coal seam; 'The wheels721 roll along the roof of the mine as the machine-advances. An'y irregularities or resiliency of the spring 27.

roof-engaging element.

In addition to increasing the traction of the mining machine 10, the wheels 21 improve the general stability of the machine by supporting it firmly between the floor. androof of the mine. Thus when a cutter bit 18 encounters an area of hard material, the machine 10 cannot rise up in reaction, but instead the cutter bits 18 are held firmly against the hard material and forced to penetrate while in contact with the hard material. Thus the cutter bits 18 do not bounce off the face of the seam, but instead individually simulate the operation ofa machine shop lathe.

To retract the roof-engaging structure, the machine operator turns the valve 51 (Figure 4) ma position in which the conduits 52 and 55 are joined and are out of communication with theconduit 49. Thereupon the needle valve 53 is opened and hydraulic pressure from the hydraulic cylinder chamber 42 is released through the conduits 52 and 55 to the fluid reservoir 46.

As indicated in Figure 2, I prefer to use my roofengaging elements in pairs, placed laterally of the longitudinal axis of the machine. When the roof-engaging elements are supplied in pairs as shown in Figure 2, I prefer to have an independent hydraulic source for each It is possible, of course, to operate both roof-engaging elements from a common source of pressurized hydraulic fluid.

An alternative embodiment is illustrated in Figure 6 where one pair of roof-engaging elements is mounted at the forward end of the machine 10 and a second pair of roof-engaging elements is mounted at the rear of the machine It). By providing a source of hydraulic fluid for the forward elements independent of the rear elements, thereby providing independent control of the forward and rear hydraulic jacks, it is possible to regulate the relative upward thrust from each roof-engaging structure. In addition to providing sensitive control over the apparent center of gravity of the machine, this feature permits the operator to steer the mining machine 10 in a vertical direction. Should the coal scam in which the mining machine 10is operating slant downwardly, the machine can be made to follow the seam by merely releas ing the upward thrust on the rear roof-engaging structure. Thereupon the forward element urges the front of the machine 10 downward. Similarly, if the coal seam ascends, the machine can be steered vertically upward by releasing the thrust of the forward roof-engaging structure, thereby permitting the rear roof-engaging structure to urge the front of the machine upward. With existing mining machines, vertical steering is a difiicult and time consuming operation.

To cause existing machines to rise in line with an ascending coal seam, it is necessary to elevate jacks under the forward end of the frame. These floor jacks must be released and repositioned as the machine advances until its direction of motion follows that of the seam. To cause an existing machine to descend in line with a descending coal scam, the heavy cutter head is dropped to its bottom position and the descent is attained through the resulting unbalance of the machine. The improvement shown in Figure 6 permits the machine operator to steer it in a vertical plane by merely turning manual hydraulic valves. 7

The apparatus shown in Figure 6 corresponds to that of Figure 1; corresponding numerals are employed to indicate corresponding parts. A generally horizontal rail 60 is mounted above the frame 11 on the elevated supporting structure 22. In the forward end of the machine a spring 61 is maintained between the supporting structure 22 and a sliding block 62. A sliding block 63 on the rail 60 engages a piston rod 64 which is operated by a hydraulic cylinder 65. Upwardly extending arms 66 and 67 are supported by pin joint journals in the blocks 62 and 63 respectively and joined in pivotal coplanar relation at their upper ends. The operation of the upwardly extending arm 66 is the same as that of the up- 6 wardly extending arm 29 described in Figure 1. A roofengaging element 68, corresponding to 21 of Figure l, is provided at the'top of the element 66 in the manner shown in Figure 5.

A second roof-engaging structure in the rear of the mining machine includes a spring 69 mounted between the supporting structure22 and a sliding block 70. Another sliding block 71 engages a piston arm 72 which is operated by a hydraulic cylinder 73 mounted on the supporting structure 22. Upwardly extending arms 74 and 75 are mounted in pin joint journals on the blocks 7% and 71 respectively and joined in pivotal coplanar relation at their upper ends. A roof-engaging wheel 76, corresponding to element 68, is mounted above the upwardly extending element 74in the manner shown in Figure 5.

Preferably the hydraulic fluid operating the cylinders 65 and 73 is subject to independent control by the machine operator through a hydraulic circuit corresponding to that shown in Figure 4-. Independent control of the hydraulic cylinders 65 and 73 permits the operator to control steering of the machine in a vertical plane. In addition the independent control of the two hydraulic cylinders provides a sensitive means for regulating the apparent'center of gravity of the machine 10. By exerting greater force of the hydraulic cylinder 73, the inherent unbalance of the machine 10, resulting from the forward location of the heavy cutter head 15, can be counterbalanced.

In place of wheels as the roof-engaging element, it is possible to use some form of moving endless belt (rubber sheet, metal plates, flexible metal sheet and the like) or endless treads to distribute the compressive stress against the roof of the mine over a wider area. One example of such apparatus is illustrated and described in Figure 7.

The frame of a mining machine is provided with supporting structure 131 to support the roof-engaging apparatus of the mining machine. Mounted upon the supporting structure 131 in rigid relation to the frame 13% are a sliding rail 132 in a generally horizontal position and a hydraulic cylinder 133 of a hydraulic jack 134. A piston rod 135 extending from the hydraulic jack is secured at its outermost end to a sliding block 136 which is free to slide longitudinally along the rail 132. A mechanical spring 137 is provided at the opposite end of the rail 132 to resist motion of a sliding block 138. A central sliding block 139 is provided, freely slidable along the rail 132. Each of the sliding blocks 136, 5.33 and-139 is pin connected to lever arms 140. The lever arms 140 between adjacent sliding blocks are pin connected to second blocks 141 and 142 which are mounted upon and at the same time support in a generally horizontal position a rail 143. One of the blocks 141 and 142 is rigidly mounted on the rail 143; the other is free to slide along the rail 143. A series of rollers having parallel axes which are generally horizontal and are perpendicular to the longitudinal axis of the mining machine is provided, journaled in a generally horizontal supporting structure 145. The roller supporting structure 145 is parallel to and mounted in rigid relation to the rail 143. An endless belt or endless tread 146 is provided to encircle the rollers 144 in slidable relation.

Introduction of hydraulic fluid into the hydraulic cylinder 133 causes the piston 135 to advance against the block 136. The force exerted against the block 136 is transmitted equally in an upward direction against the sliding blocks 141 and 142, resulting in a compressive force against the roof of the mine, distributed over the area in contact with the endless belt 146. As indicated in Figure 7, the rollers are merely idlers whose function is to distribute the compressive stress uniformly over the area of the endless belt 146. If desired, one or more of the rollers 144 may be equipped with driving means (not shown) to convert the tread 146 into a driving apparatus.

I The'present invention also is applicable toiinderground vmachine's, other than mining machines, for example, tunnel'borin'g'machines and the like. i i

According to the provisions of the patent statutes, I have explained the principle, preferred construction, and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended'claims, the invention may, be practiced otherwise than as specifically illustrated and described.

I claim:

1. In an underground mobile machine having a working element at its forward end, said machine adapted to advance continuously into a working face behind said working element, the improvement comprising in combination a rigid supporting structure extending upwardly from the frame of said machine for supporting at least one generally horizontal rail extending longitudinally above said machine, a hydraulic ram mounted in fixed relation to said frame, two blocks slidably mounted upon said rail, each block having an upwardly extending strength member pivotally mounted thereon, said strength members being pivotally joined at their upper ends, rotatable roof-engaging elements having an endless surface mounted above the upper ends of said strength members, piston means associated with said ram for advancing the first block toward the second block, resilient means for resisting movement of said second block away from said first block, and means for introducing hydraulic fluid under pressure into said ram to advance said piston means. V V

2. In an underground mobile machine having a work ing element at its forward end, said machine adapted to advance continuously into a working face l hind said working element, the improvement comprising in combination at least one generally horizontal rail on each side of said machine, supported above and in rigid relation to the frame of said machine, a hydraulicram for each rail mounted in rigid relation to said frame, a first block and a second block each slidably mounted; upon each rail, an upwardly extending strength member pivotally mounted upon each block, means for joining in pivotal relation the upperends of the strength members associated with a common rail, rotatable roof-engaging elements having an endless surface mounted upon and above said strength members for engagihg a mine ceiling, piston means associated with each hf said rams-for'advancing said first blocks toward said second blocks, resilientmean for resisting movement of said second blocks away from said first blocks, and means for introducing pressurized piston means. I i

3. In an underground mobile machine having a working element at its forward end, said machine adapted to advance continuously into a Working face behind said working element, the improvement comprising incombination two generally horizontal rails mounted above the frame of said machine in rigid relation thereto and laterally spaced apart from and parallel to-thelongitudihydraulic fluid into each of s'aid rams to'adv-ance said.

nal axis'of said machine, a forward block slidably mount- ,ed'u'pon' each of'said rails, resilient meansfor resisting forward 'advance'of 'said'forward block, a central block s1idsb1y'mountea'u on'eacnor said rails, a rear block slidably fiio'unted'upoir each of said rails, hydraulic means lmounted in rigid relation to the frame of said machine including piston means for advancing each of said rear blocks respectively toward each of central blocks, a for Ward pair of upwardly extending strength members pivotally joined at their upper ends and pivotally mounted respectively to those forward blocks and those central mwksassbdatea on a common rail, a rear pair of upwardlyl extending'strength members pivotally joined at theirfupp'er ends and pivotally mounted respectively to those central blocks and those rear, blocks associatedon a commonrail, roof-engagingelements comprising a plurality of parallel rellers journalled in a generally horizontal plane above, the upper ends of said strength members, said roof-engaging elements being mounted in fixed relation to the pivot juncture of said forward strength mem bers andmo unted in slidable relation to the pivot juncture of :said rearstrength members, and means for supplying pressurized fluid to said hydraulic means foradvancing said piston means. 7 a

4. In an underground mobile machine having a working element at its forward end, said machine adapted to advance continuously into a working face behind said working element, the improvement comprising in combination a rigid supporting structure extending upwardly from the frame of said machine for supporting at least one generally horizontal rail extending longitudinally above said machine, at least one pair of blocks slidably mounted upon said rail, at least one pair of upwardly extending strength members pivotally mounted at their lower ends to'adjacent blocks and being pivotally joined at their upper ends, rotatable roof-engaging elements having an endless surface mounted above the upper endsof said strength members, hydraulic means for advancing adjacent blockstoward each other, and resilient means operative to counteract said hydraulic means whereby the advance of adjacent blocks toward each other is resisted.

5. The apparatus of claim 4 wherein the-rotatable roofengaging elements comprise at leastv one wheel, being caster-mounted to therear of the pivotally joinedupper ends of the upwardly extending'strength member.

References Cited in the file of this patent j UNITED STATES PATENTS Belgium July 15, 1950 

